The present invention relates to a sheet post-processing device which is provided to an image forming device having functions of copying, facsimiling, printing, and the like, and which feeds out sheets of paper supplied from the image forming device after performing a post-processing operation such as a stapling operation with respect to the sheets of paper.
A recent copying machine is designed so as to be used in combination with an automatic document transporting device and a sheet post-processing device, for realizing automation of a copying operation, and automation of a stapling operation or a punching operation with respect to sheets of paper having been subject to the copying operation, and the like.
The sheet post-processing device is a device which performs a post-processing operation such as stapling or punching with respect to sheets of paper which are fed out of a copying machine after original images are copied thereon, so that every stack of paper, which is composed of a predetermined number of sheets of paper, is stapled or punched.
For example, one conventional sheet post-processing device is disclosed by the U.S. Pat. No. 5,072,920 (the Japanese Publication for Laid-Open Patent Application No. 3-227694/1991 (Tokukaihei 3-227694)). FIG. 22 is an explanatory view illustrating an arrangement of a sheet post-processing device 100 disclosed by the publication.
In the sheet post-processing device 100, sheets of paper fed out of a copying machine main body are fed in through a feed-in opening 108. Then, in the case where the stapling operation is applied to the sheets, the sheets are guided by a gate 101 to a path 102.
The sheets transported through the path 102 are introduced to a staple tray 103 from its bottom upward, so that the sheets are stacked thereon.
When a predetermined number of the sheets are stacked on the staple tray 103, a stapling operation is applied by a stapler 104 to a lower edge of the sheets thus stacked. The stack of paper thus stapled is moved upward, with its lower edge pushed up by a discharge belt 105, and the stack of paper is brought up till being discharged onto a discharge tray 106. Upon discharge, the stacked sheets are transported with the edges to which the stapling operation is not applied going in front in the transporting direction.
According to the arrangement of the sheet post-processing device 100, however, the sheets to be subject to the stapling operation are fed in through the feed-in opening 108 which is positioned above the staple tray 103. The sheets are transported through the path 102 and introduced onto the staple tray 103 from below, thereby being stacked thereon.
For this reason, the path 102 is curved substantially in a U shape in the vicinity of junction of the path 102 with the staple tray 103, and in the case of the aforementioned arrangement, it is necessary to increase a radius of curvature of the curving part to some extent. This is because jamming of paper tends to occur during transportation in the case where the radius of curvature is set too small. Therefore, the foregoing arrangement has a drawback in that a floor area that the sheet post-processing device 100 occupies becomes large.
Further, as described above, in the sheet post-processing device, the feed-in opening 108 is formed at a position higher than that for the staple tray 103. In such an arrangement as relative position relationship between the staple tray 103 and the feed-in opening 108 is thus specified, a position for the staple tray 103 or the feed-in opening 108 is limited, thereby, for example, causing a space around the staple tray 103 to be narrowed, and limiting freedom in designing the sheet post-processing device. Such limitation is likewise caused in the case where the feed-in opening 108 is formed at a position lower than that for the staple tray 103.
Furthermore, with the foregoing arrangement of the sheet post-processing device 100, upon discharge of the stapled sheets of paper, the stacked sheets are transported with the edges to which the stapling operation is not applied going in front in the transporting direction. Therefore, upon paper discharge, the front edges of the stacked sheets tend to fan out, causing lower sheets to be bent under upper sheets.
Another conventional sheet post-processing device is arranged so that the stapler is moved to a stapling position so as to perform the stapling operation with respect to the stack of paper on the staple tray. With the foregoing arrangement wherein the stapler is moved, however, there arises a drawback in that structure of the sheet post-processing device becomes complicated, or a drawback in that the sheet post-processing device becomes bulkier.
Incidentally, jamming of paper tends to take place during transportation of paper, in the case of a sheet post-processing device which is arranged so that sheets of paper ejected from the copying machine are stacked on a post-processing tray so that the stapling operation as the post-processing operation is applied to the stack of paper thereon, and thereafter the stack of paper is discharged onto a discharge tray. In this case, a jamming sheet is not easily taken out, unless the transport path inside the sheet post-processing device is openable.
Such a structure which facilitates taking out of a jamming sheet is hereinafter referred to as a paper jam solving structure. A copying machine with such a paper jam solving structure is disclosed by, for example, the U.S. Pat. No. 4,952,989 (the Japanese Publication for Laid-Open Patent Application No. 61-239256/1986 (Tokukaisho 61-239256)).
FIG. 23 is an explanatory view illustrating a sheet transport path in the copying machine disclosed by the foregoing publication. As shown in FIG. 23, in this copying machine, a sheet (paper) is fed from feed cassettes 201 through feed rollers 202, 203, and 204 to a position below a photoreceptor 205. Subsequently, an image on the photoreceptor 205 is transferred to the sheet, and thereafter the sheet is transported to a fixing device (not shown) by a conveyer belt 206 provided with air suction means. After a fixing operation, the sheet is fed out.
Here, in the copying machine, the conveyer belt 206 is substantially horizontally disposed. Besides, the conveyer belt 206 is movably provided so as to incline downward by pivoting around a shaft 206a provided on a downstream side of a transport direction. Furthermore, a supporting member 207 of the feed rollers 203 is provided vertically, and rotatably with respect to a shaft 207a provided in a bottom part of the supporting member 207.
Furthermore, the conveyer belt 206 is supported by a supporting arm 209. The supporting arm 209 has a roller 208 at its top end, and is supported by a shaft 209a provided at a bottom end thereof so that the supporting arm 209 is rotatable with respect to the shaft 209a. 
The supporting member 207 is supported by a connecting piece 210, with one side of the supporting member 207 being pinned to one end of the connecting piece 210. The other end of the connecting piece 210 is rotatably connected to a middle part of the supporting arm 209.
In the case of the foregoing arrangement, if jamming of paper takes place, the supporting arm 209 is rotated around the shaft 209a as axis in an anti-clockwise direction, as shown in FIG. 24. With the rotation, the conveyer belt 206 rotates around the shaft 206a as axis in a clockwise direction. As a result, a transport path between the photoreceptor 205 and the conveyer belt 206 is opened.
Besides, the anti-clockwise rotation (laying down) of the supporting arm 209 causes the connecting piece 210 to pull the supporting member 207. As a result, a transport path facing the feed rollers 203 is opened.
Thus, the copying machine is arranged so that only by laying down the supporting arm 209, the transport paths on the feed-in and feed-out sides with respect to the photoreceptor 205 are opened, whereby jamming of paper is easily solved.
In the paper jam solving structure of the foregoing copying machine, however, the supporting arm 209 for supporting the conveyer belt 206 is rotatably provided so that the transport path is openable. Therefore, a sufficient space is required to allow the supporting arm 209 to rotate. In other words, the aforementioned paper jam solving structure has the following drawback in that ensuring that the transport path can be sufficiently opened makes it difficult to form the copying machine thinner.
The first object of the present invention is to provide a sheet post-processing device arranged so that limitation on positions of a post-processing tray (stapling tray) and a feed-in opening of the sheet post-processing device is small.
The second object of the present invention is to provide a sheet post-processing device which is capable of stably discharging sheets of paper while which is neither complicated nor bulky.
To achieve the aforementioned first object, the sheet post-processing device of the present invention comprises (1) a feed-in opening through which sheets of paper fed out of an image forming device are supplied, (2) a post-processing tray on which the sheets of paper are stacked, and (3) a post-processing section for applying a post-processing operation to the sheets of paper stacked on the post-processing tray, and is characterized in that the feed-in opening is positioned not higher than a position of an upper edge of the post-processing tray and not lower than a position of a lower edge of the post-processing tray.
With the foregoing arrangement, a part of the post-processing tray is positioned higher than the position of the feed-in opening. Consequently, the limitation on the positions of the post-processing tray and the feed-in opening in the sheet post-processing device can be made smaller.
Furthermore, with the foregoing arrangement, the post-processing tray can be disposed in an upper part of the sheet post-processing device. Therefore, it is possible to ensure a sufficient discharge capacity even in the case where the post-processed sheets of paper are fed out through the lower edge of the post-processing tray onto the discharge tray, without bringing them up.
Furthermore, to achieve the second object, the sheet post-processing device of the present invention comprises (1) a post-processing tray, (2) a post-processing section for applying a post-processing operation to edges of one side of the sheets of paper stacked on the post-processing tray, (3) a first feed-out opening for discharging, to outside, the sheets of paper having been subject to the post-processing operation, (4) a first discharge transport path for transporting the sheets of paper from the post-processing tray to the first feed-out opening, and (5) a feed-out section for discharging the post-processed sheets of paper from the post-processing tray to the first discharge transport path, and is characterized in that the post-processing tray has an adjusting-moving section for adjusting the stacked sheet of paper, moving the adjusted sheets of paper to a post-processing position at which a post-processing operation by the post-processing section can be applied, and moving the post-processed sheets of paper to a discharge position at which a discharging operation by the feed-out section is applied.
With the foregoing arrangement, the sheets of paper stacked on the post-processing tray are moved to the post-processing position by the adjusting-moving section. The post-processing position is a position at which a post-processing operation can be applied to the sheets of paper by the post-processing section. Then, the sheets of paper thus post-processed are moved to the discharge position by the adjusting-moving section. The discharge position is a position at which the discharging operation can be applied to the sheets of paper by the feed-out section.
Thus, according to the foregoing arrangement, upon application of the post-processing operation to the sheets of paper stacked on the post-processing tray, not the post-processing section but the sheets of paper are moved. Therefore, with the foregoing arrangement, there is no need to provide a driving system for moving the post-processing section, and therefore, it is possible to make the sheet post-processing device simpler and smaller.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.